WO2008142538A2

WO2008142538A2 - Transfer foil, method for manufacturing panels and panel obtained herewith

Info

Publication number: WO2008142538A2
Application number: PCT/IB2008/001267
Authority: WO
Inventors: Bart Verhaeghe
Original assignee: Flooring Industries Limited, Sarl
Priority date: 2007-05-23
Filing date: 2008-05-21
Publication date: 2008-11-27
Also published as: WO2008142538A3; BE1017615A3

Abstract

Transfer foil with a print (2) which can be transferred to a substrate and adhered, wherein this transfer foil (1), apart from said print (2), comprises at least three material layers, amongst which a carrier film (3), a separation layer (4) situated between the carrier film (3) and a first side (8) of the print (2) and with which the print (2) is provided on the carrier film (3) in a separable manner, and an adhesive layer (5) situated at a second side (9) of the print (2) and with which the print (2), as aforementioned, can be adhered to a substrate, characterized in that said separation layer (4) is made as an adhesive agent.

Description

Transfer foil, method for manufacturing panels and panel obtained herewith.

This invention relates to a transfer foil, a method for manufacturing panels, as well as to panels obtained with such method.

In particular, the invention relates to transfer foil of the type comprising a print which can be transferred to a substrate and, whether or not directly, can be adhered to this substrate. Transfer foils of this kind are known as such, for example, from EP 1 208 016, and can be applied for providing the surface of substrates with a print. Herein, this may relate, for example, to the provision of a decorative print on furniture panels, floor panels, wall panels, ceiling panels and so on.

Such print may be restricted to a portion of the surface of a substrate or panel, such as to a chamfer at an edge thereof. Covering chamfers, such as bevels, with a print by means of a transfer foil is described in WO 01/96688.

Apart from said print, such transfer foil mostly comprises substantially at least three other material layers, amongst which a carrier film, a separation layer and an adhesive layer. For transferring the print or a portion thereof, the transfer foil, by means of rollers or other pressing elements, is brought into contact with the portion of the substrate that has to be covered. During the transfer, the respective portion of the print is released from said carrier film and, by means of said adhesive layer, adheres to the substrate, whether or not directly. Usually, a hot-melt glue is used for the adhesive layer, such that, for applying the print, possibly heat must be supplied, for example, by means of said pressing elements. For releasing the print of the carrier film or a portion thereof, according to prior art wax is used, such as ester wax, which is situated in said separation layer. This wax provides for that the print or the respective portion thereof is released from the carrier film as soon as a certain adherence to the panel or the substrate has been achieved by means of the adhesive layer.

With the transfer foils from the state of the art, quality differences may unperceivedly arise in the adherence of the print on the substrate or the panel. Such quality differences relate, for example, to a lower adherence than desired, either of the entire provided print or of portions of this print. Such imperfect adherence is difficult to detect and may lead to complaints from the end user. A final factory inspection of each substrate provided with a print is particularly complex, time-consuming and expensive.

The prior art transfer foils can also lead to visible quality losses. So, for example, an excess of print may be transferred, for example, because the desired print transferred and adhered to the substrate, when releasing the carrier film, draws off undesired print portions at its edges from the carrier film. Thereby, an undesired burr occurs at the edge of the desired print, which burr afterwards possibly can be removed by means of an additional polishing operation.

Another disadvantage of the prior art transfer foils further detected in the practice occurs when such transfer foils are transported in a rolled-up condition at a relatively high temperature, for example, of more than 5O⁰C. At these temperatures, the adhesive layer of the transfer foil may already be partially activated and may cause an adherence between two windings of a roll of transfer foil lying on top of each other. This adherence manifests itself, for example, between the print of the underlying winding and the carrier film of the winding lying on top. When unwinding the transfer foil, then possibly the print of the underlying winding undesiredly may get carried along together with said winding lying on top. It is noted that temperatures above 50 °C and even up to 80⁰C are not excluded when goods are transported in an unrefrigerated container and that the herein above-mentioned occurrence of undesired adherences among windings may lead to a considerable loss of usable transfer foil.

The invention aims at an alternative transfer foil, which according to preferred embodiments of the invention also offers a complete or partial solution for the above-mentioned disadvantages of the state of the art. To this aim, the invention relates to a transfer foil of the type comprising a print which can be transferred to a substrate and adhered, wherein this transfer foil, apart from said print, comprises at least three material layers, amongst which a carrier film, a separation layer situated between the carrier film and a first side of the print and with which the print is provided on the carrier film in a separable manner, and an adhesive layer situated at a second side of the print and with which the print, as aforementioned, can be adhered to a substrate, whether or not directly, with the characteristic that said separation layer is made as an adhesive agent.

According to the present invention, a separation layer made as an adhesive agent is used, contrary to the state of the art where classic waxes, such as ester waxes, are used. Due to the fact that one works with a separation layer made as an adhesive agent instead of solely with wax, the print is released from the carrier film only when a relatively high adherence of the print or the respective portion thereof on the substrate is achieved. When portions of the print do not achieve this higher adherence on the substrate, the risk that this less adhering portions still are transferred to the substrate is small, if not not-existent, as these less adhering portions then will be left on the carrier film due to the adhesive effect of the separation layer. Thereby, the less adhering portions automatically lead to defects that are visible on the substrate because the print is absent there. The absence of the print on the substrate or the panel arising in such case then can be controlled at the factory and/or automatically, such that a final inspection, for example, by means of cameras or other sensors, becomes feasible or even simple. In such case, such control system possibly may be established in line with the application of the print, and printed products, such as panels, which do not meet the quality requirements, possibly can be provided with a fresh print or can be taken from the line for any purpose, or can be marked.

Preferably, the separation layer made as an adhesive agent provides for such a high adherence that the print is not freely peelable from said carrier film. By

"freely peelable" is meant that it is possible to separate the print in a continuous manner at least from the carrier film, when the print, possibly together with other material layers of the transfer foil, as such is gripped and pulled off the carrier film. It is noted that the transfer foils from the state of the art indeed allow for such peeling off, as the classic waxes used as a separation layer in transfer foils, which waxes can not be considered an adhesive, do not prevent this.

Thus, by "not freely peelable", here then of course is meant that the print or portions thereof can not be separated from the carrier film in a continuous manner without positively supporting at least the print or the respective portions thereof, meaning without them being supported by means which are external to the carrier film. Such external means may consist of the support which is created when the print already has been adhered to a substrate by means of the adhesive layer, or of the fact that they are supported by a reinforcing layer or other material external to the transfer foil. Restricting or preventing the free peelability of the print allows restricting the herein above-mentioned risk still further, such that the detection of the quality loss can be performed with a high certainty.

The disability of the print of being freely peeled from the carrier film can be obtained, for example, by selecting the adhesive strength or the adhesive capacity of the separation layer made as an adhesive agent higher than the breaking strength of the print.

From the above, it is clear that the print indeed may be peelable, for example, when the adhesive layer provides for an adherence on a substrate, such as a panel or the like. This can be obtained, for example, in that the adherence capacity of said adhesive layer when transferring or releasing the print from the carrier film is higher than the adhesive capacity of the aforementioned separation layer made as an adhesive agent. So, for example, the adhesive capacity of said adhesive layer, during transfer, may be at least 10 percent higher than the adhesive capacity of the separation layer made as an adhesive agent. However, in order to maintain the effect of the present invention, preferably also a separation layer, made as an adhesive agent, is used, which during transfer shows an adhesive capacity which is higher than one tenth of the adhesive capacity of said adhesive layer. So, for example, the adhesive capacity of the separation layer during transfer may be higher than one-half of the adhesive capacity of the adhesive layer. Preferably, a difference in adhesive capacity between the adhesive layer and the separation layer is applied, which, during transfer, is smaller than twenty percent of the adhesive capacity of said adhesive layer.

In a preferred embodiment, the separation layer made as an adhesive agent preferably effects a connection with the print which meets the following test: forming a test specimen from the transfer foil with a width between 3 and 10 millimeters and a length of minimum 10 centimeters; forming a strip of adhesive tape with a first and a second extremity and a width larger than the width of said test specimen; - providing said strip of tape on the test specimen, over a portion of the length thereof, however, the entire width thereof, such that this strip at the first extremity terminates at a location between both extremities of the test specimen; - peeling off the print from the carrier film by means of the strip of adhesive tape by carefully unwinding the strip from its second extremity from the test specimen; and checking, as a result of the test, whether or not the print at the first extremity of the strip is peeled off further from the carrier film; applying said result as a criterion whether the test specimen meets the test, wherein, in case the print is peeled off further from the carrier film, such test specimen does not meet the test, which thus normally means that in the case that it is not possible to further peel off the print from the carrier film, such test specimen indeed meets the test.

Preferably, the separation layer made as an adhesive agent effects a connection with the print which meets said test when the latter is fully performed at room temperature. By "cautiously unwinding", any method is intended by which folds in the print are prevented and by which it is prevented that the print is being jerked. So, for example, the peeling off can be performed by winding the strip of adhesive tape starting from its second extremity from the test specimen onto a roll, wherein this roll then preferably has a diameter of three centimeters or more. In order to avoid jerks, unwinding preferably is performed with a speed that is lower than 3 centimeters per second and still better is lower than 1 centimeter per second. The above-described preferred embodiment results in a connection offering a good assurance of avoiding the burrs mentioned in the introduction and which practically can minimize the above-mentioned risk. Moreover, the test described herein allows testing the quality of the transfer foil in a simple manner. Such test can be applied randomly as an initial control. Preferably, all test specimen of a transfer foil meet the herein above-described test.

The separation layer made as an adhesive agent preferably comprises at least an adhesive, and still better at least a permanent adhesive maintaining its adhesion capacity at least in a temperature range between 23°C and 200⁰C. Still better, the adhesion capacity of such permanent adhesive remains acceptable at least up to 25O⁰C or 300⁰C.

The separation layer made as an adhesive agent may show at least one or a combination of two or more of the following features: the separation layer comprises an adhesive with one or more components of said adhesive layer; - the separation layer comprises an adhesive with the same components as said adhesive layer; the separation layer is free of wax or anyhow consists at for at least less than 50 percent of wax; - the separation layer comprises a mixture of wax and adhesive and/or comprises a modified wax yielding a particular adhesive effect; the separation layer comprises polyurethane; the separation layer comprises a rubber-based adhesive; the separation layer comprises a thermoplastic; the separation layer comprises a hot-melt glue; the separation layer comprises an acrylic or methacrylic acid ester; - the separation layer comprises an acrylate dispersion adhesive; the separation layer comprises a methacrylate resin or a methacrylate copolymer.

By means of these agents, the above-outlined advantages of the transfer foil can be achieved. A practical example of a suitable agent is found in the adhesive agent situated on common office tape. Thus, it may be possible that the transfer foil of the invention is manufactured by applying such office tape as a carrier film and separation layer and providing it with a print and an adhesive layer at the side carrying the adhesive agent. By means of experiments, the inventor has been able to find that the disadvantages of the state of the art disappear entirely or partially when applying such experimental transfer foil. It is clear that the transfer foil according to the invention can also be realized in other ways. Thus, for example, use can be made of the same construction, materials and production processes as with the known transfer foils, the only difference being that now, instead of the material which has been used for the separation layer beforehand, then a material is applied which meets the invention.

The transfer foil of the invention may have any form. Thus, it may be implemented as sheets, webs, tapes or the like, wherein the embodiment as tapes is the most suitable for being used when covering chamfers of panels, more particularly floor panels, as described in the also aforementioned WO 01/96688. Such tapes preferably have a width of 3 to 15 millimeters, and still better of 5 to 10 millimeters and preferably are transported in a coiled manner.

The invention also relates to a method for manufacturing panels of the type comprising a single-part or multipart core and a covering provided on this core, with the characteristic that for realizing at least a portion of the covering, a transfer foil with the characteristics of the invention is applied, wherein then at least a portion of the print of the transfer foil, whether or not directly, is applied or transferred on said core. From the above, it is clear that such method may have quite some advantages in respect to a method from the state of the art. For example, such method allows for a simpler and less expensive quality control. Further, it is clear that the invention also relates to a panel which is obtained by such method. This may relate, for example, to a furniture panel, a wall panel or a ceiling panel . The panels of the invention preferably relate to panels, the covering of which is substantially made as a laminate top layer, however, wherein also a portion of the covering is obtained by means of transfer printing.

It is noted that for manufacturing panels with a laminate top layer or laminate panels, press treatments may be used. To this aim, substantially two possible manufacturing ways can be applied. According to a first possibility, laminate panels may be manufactured by means of a so-called DPL process (Direct Pressure Laminate) , wherein one or more material sheets, for example, paper sheets, provided with resin are brought into a press, together with a core, for example, a wood- based core, in which press, by means of a press element, they are subjected to an increased pressure and temperature and in this manner are mutually connected in order to form a covered core material, which then can be processed to any covered panel. According to a second possibility, the laminate panels can be manufactured by means of a so-called HPL process (High Pressure Laminate) , wherein several material sheets provided with resin first are consolidated before being applied on a core, for example, before being glued onto the core.

For laminate panels, the transfer of the print or the respective portion thereof by means of the transfer printing procedure preferably takes place after said press treatments have been performed. Of course, intermediary treatments, such as dividing larger boards into smaller boards and performing profiling treatments at the edges of the obtained panels, are not excluded. Such profiling treatments may comprise forming one or more chamfers, for example, by removing a portion of the material of the laminate top layer and possibly of the core at one or more upper edges. Also, by means of the profiling treatments, functional parts may be provided, such as coupling parts, with which two panels, such as floor panels, can be connected to each other.

Preferably, the method of the invention is applied for manufacturing panels having a chamfer at least at one of their edges and still better at least at two opposite edges, wherein at least this chamfer is provided with a covering and wherein this covering then is realized at least partially by means of said transfer foil.

When transferring the respective portion of the print onto the panel, preferably a temperature is applied which is higher than 23°C and still better higher than 50⁰C, and preferably a pressure between 1 and 15 N per square millimeter is applied. It is clear that one or more material layers can be present between the core of the panel and the provided print. These can form, for example, a primer layer, whether or not having a coloring and/or levelling effect. It is not excluded that the print is provided on top of a laminate top layer.

It is noted that, when the portion of the print which has to be transferred is released from the carrier film, said separation layer, which is made as an adhesive agent, preferably remains present on said carrier film. However, it is not excluded that it is entirely or partially transferred onto the panel together with the print.

With the intention of better showing the characteristics of the invention, hereafter, as an example without any limitative character, several preferred embodiments are described, with reference to the accompanying drawings, wherein:

Figure 1 represents a transfer foil according to the invention; Figure 2 represents a transfer foil of the state of the art;

Figures 3 to 6 represent various steps in a method for testing transfer foils;

Figures 7 and 8, at a larger scale, in a view of the area indicated by F7 in figure 6, represent two possible results of the testing method of figures 3 to 6;

Figure 9 represents a floor panel according to the invention; Figure 10 represents a cross-section according to the line X-X indicated in figure 9;

Figure 11, at a larger scale, represents a view of the area indicated by FIl in figure 10;

Figure 12 illustrates a method for manufacturing panels in a cross-section according to the line

XII-XII indicated in figure 11.

Figure 1 represents a transfer foil 1 with the characteristics of the invention. To this aim, the transfer foil 1, apart from a transferable print 2, substantially comprises three material layers 3-4-5. In connection with the print 2, it is noted that this latter can be realized by means of any printing process; thus, for example, laser printing, inkjet printing or offset printing may be applied. Further, it is noted that such print 2 may be made in a uniform color as well as in the form of a pattern.

A first material layer relates to a carrier film 3 forming the basic structure of the transfer foil 1. This latter may consist, for example, of a paper film having a weight between 20 and 150 grams per square meter, or of a plastic film, such as a PVC, PET or polyester film. The thickness of the carrier film 3 preferably is situated between 10 and 100 micrometers, for example, approximately 20 micrometers. Of course, also composed carrier films can be applied, which, for example, at the underside 6 consist of a paper layer, however, at the upper side 7 consist of a synthetic film.

Above the aforementioned carrier film 3, as the second of the aforementioned material layers a separation layer 4 is applied, with which the aforementioned print 2 situated thereabove is provided on the carrier film 3 in a separable manner. In this manner, the separation layer 4 is situated between the carrier film 3 and a first side 8 of the print 2. Preferably, the thickness of the separation layer 4 is smaller than 1 micrometer and may be situated between 0.01 and 0.2 micrometers.

As a third material layer, an adhesive layer 5 is situated above the print 2, that is, at a second side 9 of this print 2, by which layer the print 2 or portions thereof can be adhered to a substrate, whether or not directly. The adhesive layer 5 may comprise, for example, a permanent acrylate dispersion adhesive or comprise a glue which has to be heat-activated, such as a hot-melt glue, for example, on the basis of polyurethane. Such adhesive layer preferably has a thickness between 2 and 10 micrometers and still better between 3 and 6 micrometers.

It is noted that in the transfer foil 1, apart from said print 2, the carrier film 3, the separation layer 4 and the adhesive layer 5, possibly still further, whether or not intermediate, material layers may be present, which, however, for simplicity's sake are not represented here. Basically, all layers may be applied which are used in the transfer foils of the state of the art. Thus, for example, a lacquer layer can be applied between the separation layer 4 and the print 2, which then is transferred onto the substrate preferably together with the print 2 and -provides a protection for the final printed product. Such lacquer layer preferably has a thickness of between 0.5 and 5 micrometers and still better between 1 and 2 micrometers. For further examples, reference is made to said EP 1 208 016.

The particularity of the transfer foils 1 of the present invention is situated in said separation layer 4, which, according to the invention, is made as an adhesive agent, for which purpose, amongst others, the agents mentioned in the introduction may be applied; such contrary to the state of the art, where such separation layer is not made as an adhesive agent, but, for example, substantially is made as a wax.

In a preferred embodiment of the invention, the separation layer 4 provides for such a high adhesion with the print 2 that the latter is not freely peelable from said carrier film 3. For clarity's sake, figure 2 represents a transfer foil 1 which does not meet the characteristics of the respective preferred embodiment and wherein therefore the print 2 is freely peelable indeed. Figure 2 clearly shows that in such case, it is possible to take the print 2 as such and to separate, peel or strip it off the carrier film 3 in a continuous manner. By "take as such" is meant that the print 2 at the location 10 of the separation is not supported by means external to the transfer foil 1. This may take place, for example, by gripping at least the print 2 manually and carefully pulling it away from the carrier film 3 at an angle, as indicated by arrow 11, without thereby jerking at the print 2.

When performing the peeling test of figure 2, the carrier film 3 preferably also is held at an extremity 12 from which the print 2 already has been removed, such that a smooth pull-off movement may take place, for example, in that the transfer foil 1 is lifted somewhat at the location 10 where the separation occurs.

Possibly, auxiliary means may also be used for starting the peeling. Thus, for example, as represented in dash- dotted line 13, an external means, such as an adhesive tape, can be adhered to the transfer foil 1, which means then can be gripped in order to start the separation of the print 2. Of course, the ability or disability of being freely peelable must be determined in a zone 14 where such external means do not support the print 2.

According to another preferred embodiment, the separation layer 4 made as an adhesive agent effects a connection with the print 2 which meets a test described in the introduction. Figure 3 illustrates the preparative steps of this test method. Herein, on the one hand, a test specimen 15 is formed from a transfer foil 1 with a width Bl between 3 and 10 millimeters and a length Ll of minimum 10 centimeters and, on the other hand, a strip of adhesive tape 16 formed with a first extremity 17 and a second extremity 18 and a width B2 larger than the width of said test specimen. As the last step in the preparation, said strip of adhesive tape 16 is provided or pressed on said test specimen 15 over a portion of the length Ll thereof, such that this strip 16 ends at the first extremity 17 at a location between both extremities 12-19 of the test specimen. It is noted that the adhesive of the strip of adhesive tape 16 is represented in solid black line. Figure 4 shows in cross-section the obtained initial test situation. As represented, it may be provided for that said strip of adhesive tape 16 at its second extremity 18 does not adhere to the transfer foil 1, such that this second extremity 18 simply can be gripped and in further performance steps of the test can be moved in the direction of the arrow 20. For performing the test, care must be taken that the adherence of the strip of adhesive tape 16 on the transfer foil 1 is at least so high that the print 2, when pulling said strip of adhesive tape 16 loose again, peels off at least in the zone 21 where it is supported by this adhesive tape 16. To this aim, properly pressing on the strip of adhesive tape 16 before starting the pulling loose thereof is recommended.

Figure 5 represents a further step in the test, wherein the print 2 is peeled off the carrier film 3 by means of the strip of adhesive tape 16 by carefully unrolling the strip 16 from the test specimen 15, starting from the second extremity 18 of the strip. As represented here, such unrolling may take place by means of an auxiliary means, such as a spool 22, wherein by a suitable selection of the auxiliary means can be prevented that jerking movements are made at the print 2 and/or that the print 2 is folded. With a spool, it is necessary to select the diameter Dl sufficiently large. A spool diameter Dl of minimum three centimeters suffices for the most applications. It is clear that a careful unrolling can also be achieved without using auxiliary means for this purpose. When care is taken that the print 2 is not subjected to sudden jerks and that the print 2 is not folded, the unrolling may also be performed manually. It is clear that the term "unrolling" in the context of the present invention does not indicate a strict unrolling movement, but solely indicates a peeling-off of the print 2 from the carrier film 3 without any folding and jerking, which preferably is made by forming a bend 23 with the print 2 at the height of the location 10 of separation, just as shown in figure 2.

Figure 5 further also shows by means of arrow 24 that the transfer foil 1 or the test specimen 15 thereof, when being unrolled, preferably is held at least at one extremity 12. Further, it is noted that for avoiding said jerking, preferably a peel-off or unrolling speed V is applied which is smaller than 3 centimeters per second and still better is smaller than 1 centimeter per second.

Figure 6 shows the situation of the test, wherein the print 2 is already peeled off up to the first extremity 17 of the strip of adhesive tape 16. As a result of the test, then it must be determined whether or not the print 2 at this extremity 17 is peeled off further from the carrier film 3 when unrolling is done beyond this extremity 17.

Figure 7 shows the result when such further peeling-off is not possible and a break 25 of the print is detected at the height of said first extremity of the strip of adhesive tape 16. Such break indicates that such test specimen 15 then meets the test explained above.

Figure 8 shows the result in case the print 2 can be peeled off further from the carrier film 3 and such test specimen thus does not meet the test .

Figure 9 in plan view shows a panel 26, in this case a floor panel, which is obtained by means of a method according to the present invention.

Figure 10 clearly shows that in this case a floor panel is concerned of the type comprising a core 27 and a laminate top layer 28 provided on this core. Herein, the top layer 28 is composed of two layers, namely a decor layer 29 which may show a print or a coloration, and a so-called overlay 30 covering the decor layer 29. Such top layer 28 may be formed on the panel 26, for example, by means of the DPL technique mentioned in the introduction. Further, the represented floor panel 26 is at least at two opposite edges 31-32 provided with coupling means 33 with which two of such floor panels 26 can be coupled to each other and can be connected to each other in a horizontal direction Hl as well as in a vertical direction Vl in order to form a floor covering. Such coupling means may also be provided on all edges, as represented in figure 9.

The floor panel 26 of figure 10 further shows chamfers 34 at least at two opposite edges 31-32, in this case with the shape of a bevel. These chamfers 34 are realized by removing the top layer 28 and in this case also a portion of the core 27 at the respective edges 31-32, for example, by means of a mechanical treatment with a cutting tool, such as by means of a milling process. It is clear that such chamfers 34 may also be formed in other manners, for example, by means of impressions .

Figure 11 clearly shows that the aforementioned chamfers 34 are provided with a covering 35, which is provided separately from said top layer 28. In this case, this covering 35 relates to a print 2, which is realized by means of a transfer printing procedure. To this aim, as figure 12 represents, a transfer foil 1 is supplied, for example, from a roll 36, and is pressed against the surface 37 of the chamfer 34 to be printed. For simplicity's sake, only two layers of the transfer foil 2 are represented, namely the carrier film 3 and the print 2.

In the example of figure 12, for transferring the print 2 on the chamfer 34 use is made of the apparatus 38 known, for example, from DE 103 52 700. The depicted apparatus 38 comprises a metal conveyor belt 39 which is heated by means of heating units 40 and is provided as an endless belt by means of wheels 41 via the transfer foil 1 against the surface 37 to be covered. In this manner, heat is supplied to the transfer foil 1, with the intention of activating the adhesive layer 5, not shown here, which comes into contact with the surface 37 to be covered. Simultaneously, the conveyor belt 39 is pressed against the surface 37 to be covered by means of pressing rollers 42 or other pressure elements via the transfer foil 1. Herein, preferably pressures between 1 and 15 N per square millimeter are achieved. The temperature may be higher than 200⁰C, however, preferably remains below 300°C.

It is clear that the floor panel 26 preferably is moved along said apparatus 38 and that the cooperation between the surface 37 to be covered and said apparatus 38, in particular said conveyor belt 39, determines the supply of the transfer foil 1.

When the transfer foil 1 leaves the conveyor belt 39, it is preferably cooled over a certain zone 43 by means of cooling rollers 44 before the print 2 is separated from the carrier film 3. In the case of heat-activatable adhesive layers 5, the cooling is desirable in order to increase the adherence of the adhesive layer 5 during separation and in order to keep the pass-through speed W, with which the panel 26 is moved along the apparatus 38, high.

It is noted that the print at the location 10 of separation is supported by the panel 26, such that the separation is rather trouble-free, even when one works with transfer foils which are not freely peelable or which meet the test described in figures 3 to 7. Working with this kind of transfer foils even is preferred in the method of the invention. As reported above, a bad adherence of such transfer foil 1 with a high certainty results in a visible defect, such that in a simple manner an inspection of the applied print 2 can be performed immediately after the separation or at least in line with the separation. This is schematically represented in figure 12 with the sensor 45.

It is noted that the application of the print 2 is performed at a pass-through speed W of at least 50 meters per minute or even up to 100 meters per minute.

Further, it is noted that to this aim also other apparatus 38 can be applied than the one schematically depicted in figure 12 and that one doesn't necessarily have to work with a heat-activatable adherence layer 5.

Further, it is also noted that the thicknesses of the respective layers represented in the figures are shown purely in a schematic manner and that these layers, on the one hand, may strongly differ in thickness in mutual respect and, on the other hand, in respect to the length of such foil may show a considerably smaller thickness than represented here.

Of course, also other particular features can be integrated into the transfer foil according to the invention, such as, for example, applying a print which, in transferred condition, yields a relief at the printed surface, wherein this relief then may or may not be in register with a pattern possibly present in the print.

The present invention is in no way limited to the herein above-described embodiments, on the contrary may such transfer foils, methods and panels be realized according to various variants, without leaving the scope of the present invention.

Claims

Claims .

1.- Transfer foil of the type comprising a print (2) which can be transferred to a substrate and adhered, wherein this transfer foil (1) , apart from said print (2), comprises at least three material layers, amongst which a carrier film (3), a separation layer (4) situated between the carrier film (4) and a first side (8) of the print (2) and with which the print (2) is provided on the carrier film (3) in a separable manner, and an adhesive layer (5) situated at a second side (9) of the print (2) and with which the print (2) , as aforementioned, can be adhered to a substrate, characterized in that said separation layer (4) is made as an adhesive agent.

2.- Transfer foil according to claim 1, characterized in that the separation layer (4) made as an adhesive agent provides for such a high adherence that the print (2) is not freely peelable from said carrier film (3).

3.- Transfer foil according to claim 1 or 2, characterized in that the separation layer (4) made as an adhesive agent effects a connection with the print (2) which meets the following test: forming a test specimen (15) from the transfer foil (1) with a width (Bl) between 3 and 10 millimeters and a length (Ll) of minimum 10 centimeters; - forming a strip of adhesive tape (16) with a first extremity (17) and a second extremity (18) and a width (B2) larger than the width (Bl) of said test specimen (15) ; providing said strip of adhesive tape (16) on the test specimen (15), over a portion of the length

(Ll) thereof, however, the entire width (Bl) thereof, such that this strip (16) at the first extremity (17) terminates at a location between both extremities (12-19) of the test specimen (15); peeling off the print (2) from the carrier film (3) by means of the strip of adhesive tape (16) by unrolling the strip (16) from its second extremity (18) from the test specimen (15) with a speed (V) which is smaller than 1 centimeter per second; and checking, as a result of the test, whether or not the print (2) at the first extremity (17) of the strip (16) is peeled off further from the carrier film (3); applying said result as a criterion whether the test specimen (15) meets the test, wherein, in case the print (2) is peeled off further from the carrier film (3) , such test specimen (15) does not meet the test.

4.- Transfer foil according to claim 3, characterized in that the separation layer (4) made as an adhesive agent effects a connection with the print (2) which meets said test when the test in its totality is performed at room temperature.

5.- Transfer foil according to any of the preceding claims, characterized in that the separation layer (4) made as an adhesive agent comprises at least permanent adhesive, which preferably keeps its adhesion ability at least in a temperature range between 23°C and 200⁰C.

6.- Transfer foil according to any of the preceding claims, characterized in that the separation layer (4) made as an adhesive agent shows at least one or a combination of two or more of the following features: - the separation layer (4) comprises an adhesive with one or more components of said adhesive layer (5) ; the separation layer (4) comprises an adhesive with the same components as said adhesive layer (5) ; the separation layer (4) is free of wax or anyhow consists at for at least less than 50 percent of wax; the separation layer (4) comprises a mixture of wax and adhesive; the separation layer (4) comprises polyurethane; the separation layer (4) comprises a rubber-based adhesive; the separation layer (4) comprises a thermoplastic; the separation layer (4) comprises a hot-melt glue; the separation layer (4) comprises an acrylic or methacrylic acid ester; - the separation layer (4) comprises an acrylate dispersion adhesive; the separation layer (4) comprises a methacrylate resin or a methacrylate copolymer.

7.- Transfer foil according to any of the preceding claims, characterized in that it is made as a tape and in particular as a tape of the type for covering chamfers at panels, more particularly floor panels.

8. - Method for manufacturing panels of the type comprising a single- or multi-part core (27) and a covering provided on this core (27), characterized in that for realizing at least a portion of the covering, a transfer foil (1) with the characteristics of any of the preceding claims is applied.

9.- Method according to claim 8, characterized in that it is applied for manufacturing panels having at least at one of their edges (31-32) and still better at least at two opposite edges (31-32) a chamfer (34), wherein at least this chamfer (34) is provided with a covering (35) and wherein this covering (35) is realized at least partially by means of said transfer foil (1) .

10.- Panel, characterized in that it is obtained with a method according to claim 8 or 9.

11.- Panel according to claim 10, characterized in that it concerns a floor panel (26) , a furniture panel, a wall panel or a ceiling panel obtained at least by means of a DPL technique.